Looper mechanism for blind-stitch sewing machine



F. PARRY June 17, 1952 LOOPER MECHANISM FOR BLIND STITCH SEWING MACHINE Filed Sept. 22, 1949 2 SHEETS-SHEET l Fran/e Parry Mme/ 1;

June 17, 1952 PARRY 2,601,054

LOOPER MECHANISM FOR BLIND STITCH SEWING MACHINE Filed Sept. 22, 1949 2 SHEET$--SHEET 2 Patented June 17, 1952 LOOPER MECHANISM FOR BLIND-STITCH SEWING MACHINE Frank Parry, Bridgeport, Conn., assignor to The Singer Manufacturing Company, Elizabeth, N. J., a corporation of New Jersey Application September 22, 1949, Serial No. 117,160

Claims.

This invention relates to sewing machines and more particularly to an improved looper mechanism for a single thread chain-stitch blind-stitch sewing machine of the type disclosed in the U. S. patent of C. A. Deai born, No. 814,642, dated March 6, 1906.

In the machine disclosed in the above mentioned Dearborn patent, the looper is actuated by a crank having a crank-pin disposed so that its axis is arranged at an inclination to the longitudinal axis of the shaft carrying the crank. The manufacture of this inclined crank within the required tolerances involves a relatively costly procedure. Also, when an inclined crank is employed, it is customary to use a crank-pin embracing sleeve to impart the necessary compound motion to the looper. While this looper driving actuator is satisfactory in imparting the necessary motions, it requires considerable lubrication and more particularly so during high speed operation of the machine.

It is the primary object of the present invention to simplify the looper driving mechanism to the extent that a looper-actuating crank may be used having a crank-pin disposed parallel to the longitudinal axis of the shaft carrying the crank.

Another object of the invention is to provide the looper mechanism of a blind-stitch sewing machine with an anchor link, whereby the rotary actuator for the looper may comprise a simple crank.

The foregoing and other objects and advantages, together with means whereby the same may be carried into effect, will best be understood from the following description of a preferred embodiment thereof illustrated in the accompany-' ing drawings, in which:

Fig. 1 is a left side elevational view of a blindstitch sewing machine embodying my improved looper mechanism.

Fig. 2 is a horizontal sectional view taken substantially along the line 2-2, Fig. 1.

Fig. 3 is a vertical sectional view taken substantially along the line 3-3, Fig. 1'.

Fig. 4 is a vertical sectional view taken substantially along the line 4-4, Fig. 1.

Referring to the drawings, the machine illustrated is one of the well known single thread blind-stitch sewing machines and comprises a frame including a bed II] to one end of which is pivoted a work-supporting frame I I and from the other end of which rises a standard I2 terminating in a forwardly extending arm I3. J ournaled in the standard I2 is a rotary main-shaft I4 carrying at one end a belt-driven pulley IS in the manner clearly shown in the previously mentioned Deanborn Patent No. 814,642. Journaled in the forwardly extending arm I3 is a rock-shaft I6 actuated at one end by means of a rock-arm I1 and pitman I8 (Fig. 4) from a crank I9 carried by the rotary shaft M. At its other end, the rock-shaft I 6 has clamped upon it a needlecarrier 20 in which is fastened a curved needle 2!. As is customary in blind-stitch machines, the curved needle during the normal course of sewing enters and emerges from the material on the same side thereof. The material to be stitched is adapted :to be advanced past the needle 2| by a feed-dog 22 carried on the free end of a feed-Ibar 23, which feed-bar is fulcrumed intermediate its ends on a pivot-pin 24 (Figs. 1 and 3) carried in the upper portion of an oscillatory link 25 supported by a short shaft 26 journaled in the arm I3 of the machine frame. At its end remote from the feed-dog 22, the feed-bar 23 is enlarged to embrace an actuating eccentric 21 carried by the main-shaft I4. Rotation of the main-shaft I4 will impart substantially a fourmotion travel to the feed-dog 22, which feed-dog engages the top of the work and, during its workadvancing stroke, is opposed. by the work-supporting frame II.

Cooperating with the thread-carrying curved needle 2| in the formation of single thread chainstitches is a looper 28 of conventional construction. The looper 28 is adjustably mounted in an offset looper-clamp 29 which is secured on one end of a looper-carrying shaft 30 journaled for oscillation in the spaced bearing lugs 31 and 32 of a looper-frame 33. At its rear end, the looperframe 33 is apertured to receive a needle-bearing 34 (Fig. 2) mounted on a crank-pin 35 having its axis disposed parallel to the longitudinal axis of the main-shaft I 4. The crank-pin 35 is preferably formed on a mounting plate 36 having a centrally disposed locating projection 31 and an arcuate slot 38 (Fig. 1) through which extends a clamping screw 39 threaded into a disk or counterweight 40 of the needle-actuating crank I9. The purpose of the arcuate slot 38 and the clamping screw 39 is to permit adjustment of the crankpin 35 about the locating projection 31 to change the timing of the looper "28 with respect to the needle 2|.

It will be understood that in blind-stitch sewing machines of the type illustrated in the drawings, the looper after advancing to enter and seize the thread-loop presented by the needle carries the seized thread-loop upwardly and backwardly over the material and then downwardly to position the seized needle-thread-loop for entrance by the needle just before said needle penetrates the work on its next stroke. Controlled up-and-down motions of the looper 28 are obtained by pivotally supporting the looperframe 33 at the lower end of a depending link 4| which is fulcrumed at its upper end on a shouldered pivot-stud 42 having an offset shank 43 located eccentrically in a bushing 44 secured by set screws 45 for turning adjustment in the arm l3. The lower end of the depending link 4| is bifurcated (Fig. 3) to provide two limbs 4| and 4| which are preferably spaced to just engage the sides of the looper-frame 33, whereby the looper-frame is steadied and any cramping action between the looper-frame and the crank-pin 35 is minimized. A cap-screw 46 threaded into the end of the pivot-stud 42 retains the link 4| on the pivot-stud.

In addition to the up-and-down and the backand-forth motions of the looper 28, the same is oscillated about the longitudinal axis of the looper-carrying shaft 30 to properly position and spread the thread-loop for entrance by the needle. The oscillations of the looper are obtained by means of an anchor-link connection between the looper-carrying shaft 30 and the stationary arm l3. As shown in Figs. 1 and 4, the looper-carrying shaft 30 has clamped on it a short rock-arm 4i terminating in a ball 48 embraced by the socketed lower end of an extensible anchor-link 49 connected at its upper end by. a stud 50 to the machine-arm l3. As the looperframe 33 travels in response to the rotation of the crank-pin 35 and the swinging movement of the link 4|, the anchor-link 49 causes the loopercarry shaft 30 to turn in its supporting bearing lugs 3| and 32.

From the above description, it will be understood that the necessary looper motions are derived from a simple rotary crank which is mounted directly on the main-shaft of the machine. Not only is the crank 35 simple to manufacture, but by having the crank 35 fastened for limited circular adjustment about the axis of the shaft |4, as by the slot 38 and the screw 39, convenient adjustment in the looper timing may be made. Facilitating the proper timing and positioning of the looper 28 relative to the curved needle 2|, is the eccentrically mounted pivot-stud 42 for the depending link 4|; adjustment of the sleeve 44 in which the pivotstud 42 is mounted serving to raise or lower the looper 28. Additional adjustment of the looper 28 can be obtained by turning the offset looperclamp 2e on the looper-carrying shaft. 30, by turning the looper 28 in the looper-clamp 29, and/or by adjusting the length of the anchorlink 49. It will be understood that the provision of the anchor-link 49 not only simplifies the type of rotary actuator 35 employed for actuating the looper 28, but it also permits the oscillatory motions which are imparted to the looper 28 to be reduced to the minimum required for proper stitch-formation. In other words, by properly locating the anchor-link 49 with respect to the rotary crank 35 and the link 4| the required minimum oscillation of the looper can be obtained. In prior machines in which the looper is actuated by an inclined crank, the inclination of the crank must be such as to satisfy a plurality of critical positions of the looper relative to the needle and, in satisfying certain of these, the inclination of the crank is determined, leaving the oscillations of the looper about the longitudinal axis of the looper-shaft excessive. The design of my improved mechanism is such that the exact amount of oscillation of the looper can be obtained without in any way affecting the design ordimensions of the rotary actuator 35.

Having thus described the nature of my invention, what I claim herein is:

1. A looper mechanism for a blind-stitch sewing machine having a machine-frame and a thread-carrying needle, comprising a looper complemental to said needle in the formation of chain-stitches, a looper-carrying shaft, a movable looper-frame in which said shaft is journaled, means supporting said looper-frame, a rotary actuator operatively connected to said looperframe, and an anchor-link operatively connected to said looper-carrying shaft and to said frame and arranged to oscillate said shaft relative to said looper-frame when said looper-frame is actuated.

2. A looper mechanism for a blind-stitch sewing machine having a main actuating shaft and a thread-carrying needle; comprising a looper complemental to said needle in the formation of chain-stitches, a movable looper-frame, a member supporting one end portion of said looperframe, a crank-pin carried by said main actuating shaft and operatively connected to said looper-frame, said crank-pin having its axis disposed parallel to the longitudinal axis of said main actuating shaft, a looper-carrying shaft journaled in said looper-frame, and an anchorlink operatively connected to said looper-carrying shaft and arranged to oscillate said loopercarrying shaft relative to said looper-frame when the latter is actuated.

3. A looper mechanism for a blind-stitch sewing machine having a frame in which is journaled a main rotary shaft, and a needle operatively connected to said shaft; comprising a looper complemental to said needle in the formation of stitches, a movable looper-frame, a link pivotally supported on said frame and bifurcated at one end to straddle and pivotally carry one end of said looper-frame, a rotary crank-pin carried by said main shaft and operatively connected to said looper-frame, a looper-carrying shaft journaled in said looper-frame, a rock-arm clamped on said looper-carrying shaft, and an anchorlink connected at one end to said rock-arm and at its other end connected to said frame.

4. A looper mechanism for a blind-stitch sewing machine having a frame in which is journaled a main rotary shaft, and a needle operated by said rotary shaft; comprising a looper complemental to said needle in the formation of stitches, a movable looper-frame, a member pivotally supporting one end portion of said looper-frame, a crank-pin carried by said rotary shaft and operatively connected to said looper-frame, said crank-pin having its axis disposed parallel to the longitudinal axis of said main rotary shaft, a looper-carrying shaft journaled in said looperframe, a rock-arm clamped on said looper-carrying shaft, and an anchor-link connected at one end to said rock-arm and at its other end adapted to be connected to said frame, said anchor link being constructed so that its length can be regulated to change the timing of the looper with respect to said needle.

5. A looper mechanism for a blind-stitch sewing machine having a machine-frame provided with a main actuating shaft and a thread-carrymg needle; p sing a plural-motion looper complemental to said needle in the formation of chain-stitches, a, looper-frame movablein a. single plane thereby to impart certain of the motions to said looper, means for moving said looperframe including a member supporting one end portion of said looper-frame and a rotary actuator operatively connected to the other end of said looper-frame, a looper-carrying shaft journaled in said looper-frame and movable to impart other of the motions to said looper, and means for moving said looper-shaft relative to said looperframe including a rock-arm carried by said looper-carrying shaft, and an anchor-link connected at one end to said rock-arm and at its other end to said machine-frame.

FRANK PARRY.

Name Date Dearborn Mar. 6, 1906 Number 

